# magic2.2

Four classes of cards, tallied respectively by $\overline{\sigma}$,
$\sigma$, $\overline{\mu}$, and $\mu$,
result from two types of division: spectator
versus magician and face-up versus face-down.

David is a final year PhD student at UCL studying geometric group theory. When not doing maths he can usually be found singing or playing the flute.

• ### My favourite LaTeX package

The Chalkdust editors share some of their favourites
• ### In conversation with Ulrike Tillmann

Sophie Maclean and David Sheard speak to a very top(olog)ical mathematician!

Solitons
• ### Chalkdust issue 11 puzzle hunt #3

David Sheard sets the third puzzle. Can you solve it?
• ### On the cover: Apollonian packing

David Sheard explores the rich mathematics and history behind the Apollonian packing, and the cover of issue 11
• ### Top ten vote issue 05

Vote for your favourite geometry instrument